In recent years, due to the spread of the Internet and others, the information processing amount of personal computers and the processing speed of information have been required to be increased. Following to that, it has been requested that the capacity of hard disc drives (HDDs) integrated into personal computers and the speed of information transmission are made larger. The type of the component for supporting a magnetic head used in an HDD, which is called a magnetic head suspension, has also been shifting from a conventional type, to which signal lines such as gold wires are connected, to a wiring-integrated type, i.e., the so-called wireless suspension type, wherein signal lines such as copper wires are fitted directly to a stainless steel spring.
Recently, demands for HDDs to be mounted into various small-sized devices, typical examples of which are portable devices, have been increasing. For this reason, the density of HDDs has been made higher, and further the size of magnetic heads has been becoming smaller. Thus, with an increase in the sensitivity of the magnetic heads, the magnetic heads are easily affected by electrostatic charging. Accordingly, there is caused a problem that the properties of small-sized magnetic head elements are changed by electric charges collected in their sliders, and at worst the elements are broken.
Another problem is the following problem: in order to improve the signal transmission speed and precision of HDDs, there has been a tendency that electric signals having a higher frequency are used in recent years; as the frequency becomes higher, noises of transmitted electric signals increase. It has been considered that a cause for generating noises is based on a difference in potential between the metallic substrate and the wiring layer.
Against these problems, for example, Patent Document 1 discloses the following matters for preventing a damage of a magnetic head by electrostatic discharge: the use of an electroconductive resin between the magnetic head and the suspension for the purpose of attaining electric connection; the formation of an earth electrode on the suspension side from an electroconductive material such as copper by sputtering, plating, vapor deposition or the like; and others.
For example, Patent Document 2 discloses a method to restrain the generation of noises, wherein a ground terminal is set up on a wired suspension for attaining a short circuit between wiring and a substrate for the suspension. In the process of forming the ground terminal, an additive method is used; therefore, required are the step of forming a power-feeding layer through a dry process, and the step of forming a wiring layer by electrolytic plating.
According to the above-mentioned prior arts, it is necessary to conduct a process for which a relatively long time is required, such as sputtering, plating or vapor deposition, when an earth electrode or a ground terminal is formed. For this reason, there remain problems that the productivity is low and costs increase.
Patent Document 1: Japanese Patent Application publication (JP-A) No. 08-111015
Patent Document 2: JP-A No. 2006-12205